Acetates substances

Zhao ZZ, Qin X-Z, Wu A, Yuan Y. Novel rearrangements of an N-oxide degradate formed from oxidation of a morpholine acetal substance P antagonist. J Pharm Sci 2004 93(8) 1957-1961. 

CH2CI2. A colourless liquid with a chloroform-like odour b.p. 4I°C. Prepared by heating chloroform with zinc, alcohol and hydrochloric acid manufactured by the direct chlorination of methane. Decomposed by water at 200°C to give methanoic and hydrochloric acids. Largely used as a solvent for polar and non-polar substances, particularly for paint removal (30%), dissolving cellulose acetate and degreasing (10%). It is more stable than carbon tetrachloride or chloroform especially towards moisture or alkali. It is somewhat toxic. U.S. production 1981 280000 tonnes. 

CH3COCH2CH1COCH3. Colourless liquid which becomes yellow on standing b.p. I9PC. Obtained by boiling 2,5-dimethylfuran with dilute sulphuric acid. It readily condenses with a variety of substances to give derivatives of furan, thiophen and pyrrole, and is a solvent for cellulose acetate. 

Acetylation. Place 1 ml. of the substance (or, if solid, i g. of the powdered amine) in a small flask fitted with a reflux condenser (or in a test-tube fitted with a cold-finger, as in Fig. 35, p. 62), add 5 ml. of an acetic anhydride-acetic acid mixture (equal volumes) and reflux... 

Now calculate the molecular weight of the substance precisely as described on p. 442. The weight of the solvent employed may be calculated from the following densities methanol, 0 810 rectified spirit, 0-807 acetone, 0 797 ethyl acetate, 0 905 chloroform, 1 504 carbon tetrachloride, 1 582 benzene, 0 880 toluene, 0-871 cyclohexane, 0-724 i, 2-dichloroethane, 1 252. 

It is a well-known fact that substances like water and acetic acid can be cooled below the freezing point in this condition they are said to be supercooled (compare supersaturated solution). Such supercooled substances have vapour pressures which change in a normal manner with temperature the vapour pressure curve is represented by the dotted line ML —a continuation of ML. The curve ML lies above the vapour pressure curve of the solid and it is apparent that the vapour pressure of the supersaturated liquid is greater than that of the solid. The supercooled liquid is in a condition of metastabUity. As soon as crystallisation sets in, the temperature rises to the true freezing or melting point. It will be observed that no dotted continuation of the vapour pressure curve of the solid is shown this would mean a suspended transformation in the change from the solid to the liquid state. Such a change has not been observed nor is it theoretically possible. 

If the substance is found to be far too soluble in one solvent and much too insoluble in another solvent to allow of satisfactory recrystallisation, mixed solvents or solvent pairs may frequently be used with excellent results. The two solvents must, of course, be completely miscible. Recrystallisation from mixed solvents is carried out near the boiling point of the solvent. The compound is dissolved in the solvent in which it is very soluble, and the hot solvent, in which the substance is only sparingly soluble, is added cautiously until a slight turbidity is produced. The turbidity is then just cleared by the addition of a small quantity of the first solvent and the mixture is allowed to cool to room temperature crystals will separate. Pairs of liquids which may be used include alcohol and water alcohol and benzene benzene and petroleum ether acetone and petroleum ether glacial acetic acid and water. 

Selection of solvents. The choice of solvent will naturally depend in the first place upon the solubility relations of the substance. If this is already in solution, for example, as an extract, it is usually evaporated to dryness under reduced pressure and then dissolved in a suitable medium the solution must be dilute since crystallisation in the column must be avoided. The solvents generally employed possess boiling points between 40° and 85°. The most widely used medium is light petroleum (b.p. not above 80°) others are cycZohexane, carbon disulphide, benzene, chloroform, carbon tetrachloride, methylene chloride, ethyl acetate, ethyl alcohol, acetone, ether and acetic acid. 

Attention has previously (see Diazonium Sails) been drawn to the fact that unless an excess of hydrochloric (or mineral) acid is used in the diazotisation process, coupling occurs between the diazonium salt and the amine to give diazoamino compounds. Thus phenyldiazonium chloride and aniline yield diazoaminobenzene. This substance may be conveniently prepared by dissolving two equivalents of aniline in three equivalents of hydrochloric acid, and adding one equivalent of sodium nitrite in aqueous solution followed by two equivalents of sodium acetate ... 

In a 500 ml. flask, fitted with a reflux condenser, place 53 g. of 1-chloro-methylnaphthalene (Section IV.23), 84 g, of hexamethylenetetramine and 250 ml. of 1 1 acetic acid [CAUTION 1-Chloromethylnaphtha-lene and, to a lesser degree, a-naphthaldehyde have lachrymatory and vesicant properties adequate precautions should therefore be taken to avoid contact with these substances.] Heat the mixture under reflux for 2 hours it becomes homogeneous after about 15 minutes and then an oil commences to separate. Add 100 ml. of concentrated hydrochloric acid and reflux for a further 15 minutes this will hydrolyse any SchifiF s bases which may be formed from amine and aldehyde present and will also convert any amines into the ether-insoluble hydrochlorides. Cool, and extract the mixture with 150 ml. of ether. Wash the ether layer with three 50 ml. portions of water, then cautiously with 50 ml. of 10 per cent, sodium carbonate solution, followed by 50 ml. of water. Dry the ethereal solution with anhydrous magnesium sulphate, remove the ether by distillation on a steam bath, and distil the residue under reduced pressure. Collect the a-naphthaldehyde at 160-162718 mm. the yield is 38 g. 

This substance is conveniently obtained by treating p-bromoacetophenone (Section IV, 138) with the calculated quantity of bromine dissolved in glacial acetic acid ... 

The argument for the S 2 process, when the transition from acetic acid as solvent to nitric acid as solvent is considered, is less direct, for because of the experimental need to use less reactive compounds, zeroth-order nitration has not been observed in nitric acid. It can be estimated, however, that a substance such as nitrobenzene would react about 10 faster in first-order nitration in nitric acid than in a solution of nitric acid (7 mol 1 ) in acetic acid. Such a large increase is understandable in terms of the S z mechanism, but not otherwise. 

Isoamyl acetate is the common name of the substance most responsible for the characteris tic odor of bananas Wnte a structural formula for isoamyl acetate given the information that it IS an ester in which the carbonyl group bears a methyl substituent and there is a 3 methylbutyl group attached to one of the oxygens... 

The solvent used m catalytic hydrogenation is chosen for its ability to dissolve the alkene and is typically ethanol hexane or acetic acid The metal catalysts are insoluble m these solvents (or indeed m any solvent) Two phases the solution and the metal are present and the reaction takes place at the interface between them Reactions involving a substance m one phase with a different substance m a second phase are called het erogeneous reactions... 

Many of the most interesting and useful reactions of aldehydes and ketones involve trans formation of the initial product of nucleophilic addition to some other substance under the reaction conditions An example is the reaction of aldehydes with alcohols under con ditions of acid catalysis The expected product of nucleophilic addition of the alcohol to the carbonyl group is called a hemiacetal The product actually isolated however cor responds to reaction of one mole of the aldehyde with two moles of alcohol to give gem mal diethers known as acetals... 

Esters can participate m hydrogen bonds with substances that contain hydroxyl groups (water alcohols carboxylic acids) This confers some measure of water solubil ity on low molecular weight esters methyl acetate for example dissolves m water to the extent of 33 g/100 mL Water solubility decreases as the carbon content of the ester increases Fats and oils the glycerol esters of long chain carboxylic acids are practically insoluble m water... 

Carotenoids are natural pigments characterized by a tail to tail linkage between two C20 units and an extended conjugated system of double bonds They are the most widely dis tributed of the substances that give color to our world and occur m flowers fruits plants insects and animals It has been estimated that biosynthesis from acetate produces approximately a hundred million tons of carotenoids per year The most familiar carotenoids are lycopene and (3 carotene pigments found m numerous plants and easily isolable from npe tomatoes and carrots respectively... 

Chemists and biochemists And it convenient to divide the principal organic substances present m cells into four mam groups carbohydrates proteins nucleic acids and lipids Structural differences separate carbo hydrates from proteins and both of these are structurally distinct from nucleic acids Lipids on the other hand are characterized by a physical property their solubility m nonpolar solvents rather than by their structure In this chapter we have examined lipid molecules that share a common biosynthetic origin m that all their carbons are derived from acetic acid (acetate) The form m which acetate occurs m many of these processes is a thioester called acetyl coenzyme A... 

Acetic acid is also transported ia barges, sometimes ia amounts of 1500 to 1750 tons. Acetic acid is not as hygroscopic as some other anhydrous organic substances, but barge shipments occasionahy have specification problems because of wave splashing iato the tanks or other careless handling. 

Acetamide [60-35-5] C2H NO, mol wt 59.07, is a white, odorless, hygroscopic soHd derived from acetic acid and ammonia. The stable crystalline habit is trigonal the metastable is orthorhombic. The melt is a solvent for organic substances it is used ia electrochemistry and organic synthesis. Pure acetamide has a bitter taste. Unknown impurities, possibly derived from acetonitrile, cause its mousy odor (1). It is found ia coal mine waste dumps (2). 

Ketene Process. The ketene process based on acetic acid or acetone as the raw material was developed by B. F. Goodrich (81) and Celanese (82). It is no longer used commercially because the intermediate P-propiolactone is suspected to be a carcinogen (83). In addition, it cannot compete with the improved propylene oxidation process (see Ketenes, ketene dimers, and related substances). 

Ranitidine. Ranitidine hydrochloride [66357-59-3] (Zantac) is a white to pale yellow granular substance. It is freely soluble in water and acetic acid, soluble in methanol, sparingly soluble in ethanol, and practically insoluble in chloroform. It has a slightly bitter taste and a sulfur-fike odor. It may be made by the method described in Reference 5. 

Mixtures of glycerol with other substances are often named as if they were derivatives of glycerol eg, boroglycetides (also called glyceryl borates) are mixtures of boric acid and glycerol. Derivatives, such as acetals, ketals, chlorohydrins, and ethers, can be prepared but are not made commercially, with the exception of polyglycerols. 

Naphthalene Acetic Acid and Naphthalene Acetamide. Naphthalene acetic acid [26445-01-2] (38) is historicaHy one of the first plant growth regulators. Reports concerning its activity in crops and plants have been a subject in much of the eady Hterature (57). Consequently, it has been used as a starting matedal for other compounds, eg, vide infra Sevin. Naphthaleneacetamide [31093-43-3] (39) has been used as a standard matedal to evaluate abscission pnor to 1953 and its effect on apple drop was reported in 1953 (58). The substance is used as an internal standard in the abscission bioassay (59). 

There are some chemicals that can be made economically from coal or coal-derived substances. Methanol and CO are used to make acetic anhydride and acetic acid. Methanol itself can be made from synthesis gas over a copper-2inc catalyst (see Feedstocks, coal chemicals). 

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